In fluid systems for aircraft, race cars, and in other applications where spillage of inflammable fuel or liquid may occur due to high impact forces being imposed upon the vehicle it is known to employ "crashworthy" couplings. Such couplings include frangible structure for interconnecting the valve bodies, and usually, the frangible structure is defined by weakened pins or portions utilized in the coupling interlocking components. In the event of a crash, high tension or bending forces applied to the coupling parts causes the weakened portions to fracture permitting the coupling halves to separate. Usually, each coupling half or part includes a self-sealing valve which is maintained in its open position when the coupling is in its normal operating mode. However, upon the coupling halves separating spring forces imposed upon the valves bias the valves to the closed condition preventing fluid flow and leakage from the associated conduit, such as a hose line as shown in the assignee's U.S. Pat. No. 4,643,216.
While crashworthy couplings of the aforedescribed type have proven to be dependable in operation they are not readily connectable and usually require a separate tool, such as a screwdriver or mandrel, to hold the valves in the open position as the parts are being connected until the parts are fully coupled as in the case with the assignee's Ser. No. 07/239,408, filed Sept. 1, 1988, now U.S. Pat. No. 4,884,591. This creates an inconvenience for the operator especially in situations where it is often necessary to disconnect and reconnect the coupling parts, such as when the parts are located in the wings of aircraft and must be disconnected in order to fold the wings for storage purposes.
It is an object of the invention to provide a reconnectable self-closing frangible fluid system coupling wherein the coupling parts may be quickly connected or disconnected without the use of separate tools.
A further object of the invention is to provide a reconnectable frangible fluid system coupling including a pair of coupling parts wherein at least one of the parts include frangible components and employs an operating valve and a safety valve, the operating valve utilizing the relative axial movement of the coupling part during assembly and disassembly to open and close respectively, and the safety valve being retained in an open position by valve retaining structure interposed between the two valves whereby upon fracture of the frangible components the safety valve will close automatically sealing the part to prevent spillage of fluid.
Yet another object of the invention is to provide a reconnectable frangible fluid coupling wherein at least one of the parts includes a safety valve which will close automatically upon fracture of the coupling sealing the coupling part's passage, yet the construction of the safety valve is such that it produces no flow restrictions in the coupling part when it is in the open position.
A fluid coupling in accord with the invention basically consists of two interconnectable parts each having a passage extending therethrough and each having a conduit attachment end for communication with a fluid source such as a hose, conduit tank, or the like, and a coupling end for coupling to one another. Each part is provided with an operating valve located within the associated passage adjacent the coupling end which engages a fixed member of the opposing part to open when fully coupled, and each operating valve has a compression spring biasing it to the closed position thereby sealing the associated passage automatically during uncoupling.
At least one of the parts also employs a safety valve in accord with the invention located intermediate the conduit attachment end and the coupling end. In the disclosed embodiment the safety valve is of a rotary ball valve type having a diametrical bore substantially equal in diameter to that of the passage. The safety valve is normally biased toward a closed position by a spring, but is retained in an open position by engagement with a valve retainer interposed between the safety valve and the operating valve whereby the bore is axially aligned with the passage such that the safety valve produces no flow restriction in the coupling part.
The valve retainer is maintained in engagement with the safety valve by releasable interlocking frangible structure which includes a fixed portion which engages and displaces the opposing parts operating valve to the open position upon coupling of the parts. Under normal operating conditions the frangible interlocking structure is of sufficient strength to maintain the valve retainer in engagement with the safety valve, but upon exceptional bending or tension forces being applied to the coupling the frangible structure will fracture permitting the valve retainer to separate from the safety valve and the safety valve to close. At the same time the valve retainer will also separate from the opposing part's operating valve permitting the operating valve to bias to its closed position.
The coupling parts utilize standard connecting means in which an annular sleeve mounted on one part supports radially displaceable detents that engage in a recess in the opposing part to interlock the parts in aligned axial communication. Thus, the coupling parts may be quickly and easily connected or disconnected with minimal fluid loss while the safety valve remains in an open position. Yet, upon fracture of the coupling frangible structure the safety valve will close to prevent fluid spillage.
If desired, the frangible interlocking structure may be released without damaging the coupling for testing purposes to insure that the safety valve is operating and will rotate to the closed position in the event of impact and fracture of the frangible components.